Ventilation system

ABSTRACT

A ventilation system comprising ducts for injecting air into and exhausting air from a room, said ducts extending side by side separated by a common partition which incorporates an opening between the ducts in which a damper member is arranged to be movable between two extreme positions, in one of which it closes the opening and in the other of which positions it blocks both ducts and opens for full recirculation of the return air from the ventilated room. A layer of heat conductive material is arranged on the inner side of the outer wall of the injection duct, said layer extending from the level at which the damper member contacts the outer wall of the injection duct in the extreme position, in which both ducts are blocked. The layer may have form of a liner member arranged on the inner side of the injection duct and extending also into the exhaust duct.

United States Patent [191 1111 3,830,145 Holt et al. Aug. 20, 1974 [54] VENTILATION SYSTEM 3,750,557 8/1973 Peill 98/33 75 Inventors: Jor en Holt Naestved; Christian 1 vidimark lilaslev Pane Hem Primary Exammer-Wfllram J. Wye

Christiansen Naetved an of Attorney, Agent, or Firm-Sughrue, Rothwcll, Mion, D e n m a rk Zinn & Macpeak [73] Assignee: Nordisk Ventilator Co. MS, [57] ABSTRACT Naestved Denmark A ventilation system comprising ducts for injecting air [22] Filed: June 7, 1973 into and exhausting air from a room, said ducts extending side by side separated by a common partition [21] Appl 7939 which incorporates an opening between the ducts in which a damper member is arranged to be movable [30] Foreign Appli ti Prior-ityb t between two extreme positions, in one of which it J 9, 1972 D k 2921 72 closes the opening and in the other of which Positions une enmar it blocks both ducts and opens for full recirculation of 52 US. Cl. 98/33 the return fmm the ventilated A layer 51 rm. c1 F24f 13/00 heat Conductive material is arranged the side [58] Field of Search 98/33 A 33 R the wall of injechm duct Said layer tending from the level at which the damper member [56] References Cited contacts the outer wall of the lIlJCCtlOl'l duct 1n the extreme posrtlon, 1n WhlCh both ducts are blocked. The UNITED STATES PATENTS layer may have form of a liner member arranged on the inner side of the injection duct and extending also asson 3,463,391 8/1969 Haegans 0 0 98/33 R mm the exhaust duct' 3,487,767 1 1970 Kristiansen 98 33 R 7 Claims, 3 Drawing Figures PATENIEUAUBZOIHH saw 2 or 2 FIG. 2

VENTILATION SYSTEM The present invention relates to a ventilation system comprising a duct for the injection of fresh air and a duct for the exhaustion of air from a ventilated room, said ducts having walls of an insulating material and extending at least on part of their length side by side, separated by a common partition which incorporates an opening between the ducts, in which a damper member is arranged to be movable between two extreme positions, in one of which it closes the opening and in the other of which positions it blocks both ducts and opens for full recirculation of the air from the room back to the room through the injection duct.

Ventilation systems of this kind are used for the ventilation of, for example, stables or barns, and by means of said damper member which is adjustable between full supply of fresh air and full recirculation of return air from the ventilated room it is possible to adapt the ventilation according to the temperature conditions in the room. It is known to adjust the ventilation automatically by controlling the damper movement by means of a termostat controlled hydraulic motor, so that the damper member can occupy any position between the above-mentioned extreme positions.

In known ventilation systems of the kind described a material risk for water condensation and ice formation has appeared to exist in periods of cold weather, and this risk applies particularly to the part of the system incorporating the recirculation damper member. Water condensation which may occur on the walls of the ducts as well as on the damper member has the effect that dust and dirt which in the ventilationof stables is inevitably carried along with the return air through the exhaust duct adhere to and remain applied to the surfaces in question as a solid layer which may be very difficult to remove. Furthermore, in winter periods there is a risk for ice formations in the part of the duct in which the hot, moist return air meets the cold air supplied from the ambient, i.e., on the damper member and the part of the wall of the injection duct situated opposite to said member. Such coatings as well as ice formations reduce materially the movability of the damper member and, as a result hereof, the damper movement may be completely blocked. Furthermore, water condensation in the injection duct may result in water dripping into the ventilated room, which in case of a stable may give rize to a serious risk for the health of the animals. In order to eliminate these disadvantages and reduce the risk for water condensation it has been proposed to heat insulate the ducts either by providing metallic tubes with an insulating layer or by manufacturing the ducts and common partitioncompletely of a heat insulating and shape-keeping material, such as mentioned herein before. It has shown, however, that at low temperatures below 5C even this measure will not be sufficient to prevent freezing of the damper member relative to the ducts when the member approaches the extreme position, in which it opens for full recirculation of the air from the exhaust duct to the injection duct, owing to the fact that at these low temperatures there will be a pronounced tendency for ice formations to occur on the inner side of the outer wall of this part of the injection duct. As a result hereof, it is usually necessary, even in case of ducts having walls of insulating material, to heat the duct in this critical place by means of, for example, electrical heating members in order to secure reliability of the system at low temperatures.

It is an object of the invention to provide a ventilation system of the kind described, i.e., in which the walls of the ducts are of an insulating material, in which system the temperature range in which a tendency may be expected for ice formations to occur on said critical place is considerably lower than in known systems.

According to the invention a ventilation system is provided, comprising a duct for the injection of fresh air and a duct for the exhaustion of air from a ventilated room, said ducts having walls of an insulating material and extending at least on part of their length side by side, a common partition separating said ducts on said part of their length and incorporating an opening between the ducts, a damper member arranged in said opening to be movable between two extreme positions in one of which it closes the opening and in the other of which positions it blocks both ducts and opens for full recirculation of the air from the room back to the room through the injection duct and a layer of a material of high heat conductivity arranged on the inner side of the outer wall of the injection duct said layer extending from the level at which the damper member contacts the outer wall of the injection duct in the extreme position of the damper member in which both ducts are blocked.

In the ventilation system according to the invention the heat conducting layer in the injection duct will be contacted at least on the lower part thereof by a mixture of the hot return air from the ventilated room passing through the recirculation opening and the ambient air supplied through the injection duct, said air mixture having a considerably higher temperature than the ambient air. The heat thus applied to the heat conducting layer is conveyed to the upper part of said layer which is located on the very place in the injection duct at which the risk for ice formations to occur is particularly pronounced, whereby the inner side of the outer wall of the injection duct on this place will attain a higher temperature, so that the risk for ice formations is materially reduced.

A further improved effect may be obtained by designing the heat conducting layer so as to extend into the exhaust duct. Thereby, the part of the layer located in the exhaust duct is contacted directly by the hot return air, so that a greater quantity of heat is supplied at this critical place.

Experience has shown that as a result of the abovementioned measures it is possible to prevent freezing of the damper member in a ventilation system according to the invention in the extreme position, in which the member opens for recirculation, down to temperatures below 25C.

In the following, the invention will be further explained with reference to accompanying drawings,.in which FIG. 1 shows an embodiment of a ventilation system according to the invention,

FIG. 2 is a cross-sectional view of the ventilation system in FIG. 1 taken along the line II-II, the damper member between the exhaust and injection duct being removed, and

FIG. 3 is a view corresponding to the sectional view in FIG. 2 of a modified embodiment.

FIG. 1 shows a ventilation system of the kinddescribed in copending US. Pat. application Ser. No.

The two concentric ventilation ducts of the fan section is connected through a connection section 3, the detailed construction of which is described in the above-mentioned U.S. Pat. application Ser. No. 268,955, with a twin-duct designated as a whole by the reference numeral 4 and comprising two substantially semi-cylindrical ducts 6 and 7 connected to the central duct and the outer annular duct of the fan section, respectively, and being separated by a common flat partition 5. The twin-duct 4 extends from the ventilated room 1 through the over-lying part of the building and terminates above the roof 8 thereof in a roof hood 9, which is designed with separate air passages for connecting the ducts 6 and 7, respectively, with the ambient air.

For the purpose of adjusting the ventilation in dependence on the temperature conditions the partition has an opening in which a control damper member 10 is arranged, said damper member being movable between two extreme positions in one of which the opening in the partition is closed, so that a complete supply of fresh air to room 1 is obtained, whereas in the other extreme position the damper member extends transversely of the ducts 6 and 7, whereby the supply of fresh air is blocked and complete recirculation of the exhaust air from duct 6 to duct 7 is established, such as described in the above-mentioned U.S. Pat. application Ser. No. 268,955.

To facilitate shipping of the ventilation system from the manufacturer to the place of installation the twinduct 4 of the embodiment shown consists of a number of shorter duct sections l1, l2, l3 and 14 which only after arrival at the place of installation is assembled in extension of each other to form the complete twinduct.

According to the invention a layer of a material of high heat conductivity is arranged on the inner side of the outer wall of the injection duct 7 in the duct section 13 which in the embodiment shown incorporates the damper member 10, said layer extending also into the exhaust duct 6. In the embodiment shown said layer is constituted by a liner member 15 of metal plate, preferably aluminium plate, the upper edge of the part of said member located in the injection duct being situated at the level at which damper member 10 contacts the outer wall of the injection duct in the extreme position, in which it blocks ducts 6 and 7 and opens for recirculation from duct 6 to duct 7. In the embodiment shown the liner member extends into exhaust duct 6, the upper edge of the part of the member located in said duct being situated at a lower level than the upper edge in the injection duct 7. Also the edge of liner member 15 facing the ventilated room 1 is obliquely cut, so that this lower edge is situated at a higher level in the injection duct than in the exhaust duct, the part of liner member 15 located in the injection duct having, however, a smaller area than the part located in exhaust duct 6.

In order to facilitate installation, the liner member 15 in the embodiment shown is subdivided by a symmetri plane, such as shown in FIG. 2, into two parts 15a and 15b, which are guided through slots 16 and 17 at opposite side edges of the part of partition 5 located in duct section 13. Due to this construction of the liner member installation may take place by introducing parts 15a and 15b into slots 16 and 17 before said part of partition 5 is arranged in duct section 13 the outer walls of which are provided with diametrically opposite grooves for the side edges of the partition.

By arranging liner member 15 in duct section 13 in the system shown in FIG. 1, the part of the liner member located in exhaust duct 6 will be contacted directly by the hot return air passing up through the exhaust duct, and the heat supplied will be conveyed through the heat conducting liner member to the very part of the injection duct 7 at which the risk for ice formations is particularly great, so that the inner side of the outer wall of the injection duct on this place attains a higher temperature at which said risk is materially reduced. The embodiment shown in which the part of the liner member located in the injection duct 7 has a smaller area than the part located in exhaust duct 6 has the ef-- fect of concentrating the supplied quantity of heat on a smaller area, so that a further improved effect is obtained.

FIG. 3 is a view corresponding to the sectional view in FIG. 2 of a modified embodiment, in which the effect of liner member 15 has been further improved by bending the portions of the two parts 15a and 15b of the liner member located in exhaust duct 6 inwardly from the outer wall of the exhaust duct, so that both surfaces of the liner member are contacted by the hot air flowing up through exhaust duct. In this embodiment the size and location of the liner member have, of course, to be chosen with due consideration to the fact that damper member 10 has to be able to occupy the abovementioned extreme position, in which it blocks ducts 6 and 7 and opens for recirculation of the return air from duct 6 into duct 7, so that the peripheral edge of damper member 10 in this position contacts the outer walls of ducts 6 and 7. Furthermore, theproportiori of the inwardly bent parts of the liner member have to be chosen so as to prevent said parts from restricting the recirculation air flow from duct 6 into duct 7 in an undesired manner.

It will be clear that the invention is not limited to the embodiment shown in the drawings since, as a matter of fact, a reduction of the risk for ice formations can also be obtained by means of a liner member along the outer wall of the injection duct, such as liner member being contacted by a mixture of the return air passing through .the recirculation opening and the ambient air supplied through the injection duct, so that the liner member is supplied with a quantity of heat which, although it is smaller than in the embodiment, shown may under conditions which are not too disadvantageous be sufficient to obtain the desired effect.

We claim:

1. A ventilation system comprising a duct for the injection of fresh air and a duct for the exhaustion of air from a ventilated room, said ducts having walls of an insulating material and extending at least on part of their length side by side, a common partition separating said ducts on said part of their length and incorporating an opening between the ducts, a damper member arranged in said opening to be movable between two extreme positions in one of which it closes the opening and in the other of which positions it blocks both ducts and opens for full recirculation of the air from the room back to the room through the injection duct and a layer of a material of high heat conductivity arranged on the inner side of the outer wall of the injection duct, said layer extending from the level at which the damper member contacts the outer wall of the injection duct in the extreme position of the damper member in which both ducts are blocked.

2. A ventilation system as claimed in claim 1, wherein said heat conducting layer is constituted by a liner member made of metal plate, preferably aluminum plate.

3. A ventilation system as claimed in claim 1, wherein said heat conducting layer extends into the exhaust duct.

4. A ventilation system as claimed in claim 3, wherein the said heat conducting layer is constituted by a liner member the parts of which located in the exhaust duct are bent inwardly from the outer wall of said duct.

5. A ventilation system as claimed in claim 3, wherein said liner member is subdivided by a symmetry plane into two parts.

6. A ventilation system as claimed in any of claim 1, wherein said heat conducting layer is limited in the direction against the injected air flow in such manner that the border of the layer is located at a higher level in the injection duct than in the exhaust duct.

7. A ventilation system as claimed in any of claim 1, wherein the heat conducting layer is restricted in the direction against the room in such a way that the area of the part of the layer located in the injection duct is smaller than the area of the part of the layer located in the exhaust duct. 

1. A ventilation system comprising a duct for the injection of fresh air and a duct for the exhaustion of air from a ventilated room, said ducts having walls of an insulating material and extending at least on part of their length side by side, a common partition separating said ducts on said part of their length and incorporating an opening between the ducts, a damper member arranged in said opening to be movable between two extreme positions in one of which it closes the opening and in the other of which positions it blocks both ducts and opens for full recirculation of the air from the room back to the room through the injection duct and a layer of a material of high heat conductivity arranged on the inner side of the outer wall of the injection duct, said layer extending from the level at which the damper member contacts the outer wall of the injection duct in the extreme position of the damper member in which both ducts are blocked.
 2. A ventilation system as claimed in claim 1, wherein said heat conducting layer is constituted by a liner member made of metal plate, preferably aluminum plate.
 3. A ventilation system as claimed in claim 1, wherein said heat conducting layer extends into the exhaust duct.
 4. A ventilation system as claimed in claim 3, wherein the said heat conducting layer is constituted by a liner member the parts of which located in the exhaust duct are bent inwardly from the outer wall of said duct.
 5. A ventilation system as claimed in claim 3, wherein said liner member is subdivided by a symmetry plane into two parts.
 6. A ventilation system as claimed in any of claim 1, wherein said heat conducting layer is limited in the direction against the injected air flow in such manner that the border of the layer is located at a higher level in the injection duct than in the exhaust duct.
 7. A ventilation system as claimed in any of claim 1, wherein the heat conducting layer is restricted in the direction against the room in such a way that the area of the part of the layer located in the injection duct is smaller than the area of the part of the layer located in the exhaust duct. 